I wrote previously about "caching" facilities to be provided by this module. This module actually has the facility but it's not implemented correctly.
After looking at the code, the ./modules/joomtunes/rss_cache.inc file looks for (and if non-existant) creates a "joomtunes/cache" directory, but it attempts to do this directly from the web root of the server (ie. to create ./joometunes/cache from your web root).
People that are security concience don't allow the webserver to write to webroot (deny all and allow only what's necessary) which is why this cache directory wasn't being created and populated in my setup.
Strictly speaking, this module should be caching its items either in the Joomla cache directory (./cache of web root which already has 777 permission), or generating it's cache directory from it's own ./modules/joomtunes/cache directory tree (so that removing the module cleans up after itself).
So to cut a long story short, to make the caching component work I needed to create this directory off my web root:
./joomtunes/cache
and assign it write privilege for the webserver.
I have emailed Gavin Smith above with this and hope that he'll implement some fixes, including cleanly removing its cache directory and tree if someone wanted to remove the module cleanly.
Thanks.
Michael.